| 1. |
- Li, Jun, et al.
(författare)
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Co-firing based on biomass torrefaction in a pulverized coal boiler with aim of 100% fuel switching
- 2012
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Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 99, s. 344-354
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Tidskriftsartikel (refereegranskat)abstract
- Torrefied biomass has several benefits, such as higher energy density, good grindability, higher flowability and uniformity. The process of torrefaction moves the chemical and physical properties of raw biomass close to that of bituminous coal, which allows co-utilization with high substitution ratios of biomass in the existing coal-fired boilers without major modifications. In this study, a torrefaction based co-firing system was proposed and studied. Devolatilization and char oxidize kinetics of the torrefied biomass have been investigated experimentally. CFD modeling of co-firing with varying substitutions of torrefied biomass in a pulverized coal boiler have been carried out. To figure out the boiler performance when co-firing torrefied biomass, five different cases were involved and simulated, coal only, 25% biomass, 50% biomass, 75% biomass, and 100% biomass on thermal basis, respectively. The results showed torrefaction is able to provide a technical option for high substitution ratios of biomass in the co-firing system. The case-study pulverized coal boiler could be fired 100% torrefied biomass without obvious decreasing of the boiler efficiency and fluctuation of boiler load. More positively, the net CO 2 and the NO x emissions significantly reduced with increasing of biomass substitutions in the co-firing system.
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| 2. |
- Li, Jun, et al.
(författare)
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Numerical analysis of loads effect on combustion performance and NO x emissions of a 220 MW pulverized coal boiler
- 2012
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Ingår i: Cleaner Combustion and Sustainable World - Proceedings of the 7th International Symposium on Coal Combustion. - : Springer Berlin/Heidelberg. - 9783540356066 - 3540356061 ; , s. 675-683
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Konferensbidrag (refereegranskat)abstract
- This paper presents numerical study on the combustion performance and NOx emissions of a 220 MW pulverized coal boiler. Three different loads have been simulated with combusting coal, 200MW, 170MW and 140MW respectively. In order to get as precise as possible numerical analysis results, two-step simulation method has been adopted in this work, namely, air supply system simulation and furnace simulation. After air supply system simulation, the results have been taken as the initial and boundary conditions for furnace simulation. The comparison between the measured values and predicted results from 200MW case shows much better agreement. According to the simulation results, the adopted two-step simulation method is reasonable and suitable for predicting the characters of the flow and combustion process. It is concluded that the distributions of temperature, O 2 and CO concentration inside furnace with different loads shows good similarly. The total NOx emissions decreased with the boiler load reducing, and fuel NOx has the same trend as total NOx, and fuel NOx account for about 66% in total NOx in all the three cases. More important, thermal NOx slowly decreased with the rise of boiler load. More detailed results presented in this paper enhance the understanding of combustion processes and complex flow patterns of Front- Wall pulverized coal boilers.
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